Protein kinase C activity and light sensitivity of single amphibian rods

J Gen Physiol. 1997 Oct;110(4):441-52. doi: 10.1085/jgp.110.4.441.

Abstract

Biochemical experiments by others have indicated that protein kinase C activity is present in the rod outer segment, with potential or demonstrated targets including rhodopsin, transducin, cGMP-phosphodiesterase (PDE), guanylate cyclase, and arrestin, all of which are components of the phototransduction cascade. In particular, PKC phosphorylations of rhodopsin and the inhibitory subunit of PDE (PDE ) have been studied in some detail, and suggested to have roles in downregulating the sensitivity of rod photoreceptors to light during illumination. We have examined this question under physiological conditions by recording from a single, dissociated salamander rod with a suction pipette while exposing its outer segment to the PKC activators phorbol-12-myristate,13-acetate (PMA) or phorbol-12,13-dibutyrate (PDBu), or to the PKC-inhibitor GF109203X. No significant effect of any of these agents on rod sensitivity was detected, whether in the absence or presence of a background light, or after a low bleach. These results suggest that PKC probably does not produce any acute downregulation of rod sensitivity as a mechanism of light adaptation, at least for isolated amphibian rods.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Ambystoma
  • Animals
  • Down-Regulation / drug effects
  • Down-Regulation / physiology
  • Electrophysiology
  • Enzyme Inhibitors / pharmacology
  • In Vitro Techniques
  • Membrane Potentials / drug effects
  • Membrane Potentials / physiology
  • Patch-Clamp Techniques
  • Perfusion
  • Photic Stimulation
  • Protein Kinase C / antagonists & inhibitors
  • Protein Kinase C / metabolism*
  • Retinal Rod Photoreceptor Cells / drug effects
  • Retinal Rod Photoreceptor Cells / enzymology*
  • Retinal Rod Photoreceptor Cells / radiation effects
  • Vision, Ocular / drug effects
  • Vision, Ocular / physiology*

Substances

  • Enzyme Inhibitors
  • Protein Kinase C